Simon Soka, Bratislava

Senior .NET engineer for payment, customs and credit systems, now also shipping whole products solo with AI agents

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me@sska.sk · sska.sk · github.com/etheaven · Bratislava, Slovakia · Slovak (native), English (C1)

Seven employers
since 2015

Newest first. Eleven years, five of them on .NET products in production.

2024 to now Own company, alongside contract work

Evolved s.r.o.

Founder and full-stack developer

  • Built and launched evolved.sk from scratch: my own fitness supplement store, a side project taking real orders. React 19, TypeScript, Vite with custom SSR, Express, MongoDB, Redis.
  • Integrated Stripe payments, webhooks and invoicing, Packeta shipping, the Heureka feed and automated EU VAT rates.
  • Built a GEO/SEO analytics SaaS that tracks brand citations across ChatGPT, Perplexity, Gemini and Claude. Next.js, Prisma, PostgreSQL, BullMQ, Stripe.
  • Coding with LLMs since 2024: aider and aichat straight on the APIs, Claude Code from its first release, Pi today.
  • Maintain a fork of codex-mcp-server, published on npm and installable as a Claude Code plugin. Delivered chensconsulting.com for a client.

Four production codebases built and run alone, with unit and E2E tests throughout. Lighthouse 93 to 96 on evolved.sk.

2025 to 2026 Contract, remote

Confidential client, under NDA

Backend and infrastructure engineer

  • Wrote the C++20 mining server behind a platform serving 10,000+ miners on 5+ continents: asynchronous networking, in-memory event storage, several proof-of-work algorithms with merged mining.
  • Implemented the protocol end to end, from job distribution and share validation to per-miner difficulty tuning.
  • Found the concurrency defects sustained load exposed, including a recursive mutex deadlock in the send path.
  • Owned the infrastructure: multi-region replication, a private-network data plane, rate-limited edge routing, containerised nodes.

Near-zero downtime on upgrades through blue/green rollout and graceful connection drain, live across multiple chains.

2023 to 2024 Ditec, remote

Slovak Financial Administration

Full-stack .NET developer at Ditec

  • Turned EU and national customs rules into implementation plans with the IT analysts, for an upgrade of the state customs system.
  • Built real-time declaration tracking on RabbitMQ for asynchronous import and export processing, with data access on Dapper.
  • Built back-office WPF screens with Prism and DevExpress, moved the codebase to DryIoc and strict xUnit and Moq tests.
  • Presented the new architecture to the Financial Administration’s stakeholders.

30% faster customs processing, and 25% less time on asynchronous declaration processing.

2022 to 2023 Itera Slovakia, remote

Mastercard Payment Services Denmark

Full-stack .NET developer

  • Worked on Betalingsservice (consumer direct debit) and Leverandørservice (B2B payments): API integrations and web portals.
  • Built high-throughput REST APIs under Mastercard’s Golden Standards compliance framework.
  • Built a fraud detection system that cut fraudulent transactions by 15%.
  • Delivered in a Slovak and Danish Scrum team on C#, ASP.NET Core, Razor Pages, Azure and Azure DevOps.

1M+ API requests a day, on payment infrastructure used by 95%+ of the Danish population.

2021 to 2022 Remote

CRIF Slovak Credit Bureau

Full-stack .NET developer

  • Developed Credit Navigator (CNAV), the portal banks, municipalities and financial institutions use for credit data and tax enforcement.
  • Built dashboards over the SRBI and NRKI credit registers for institutional clients.
  • Tuned MSSQL queries and the Entity Framework data layer behind credit report retrieval.
  • Maintained the ASP.NET MVC backend, RazorEngine document rendering and the AngularJS front end.

17+ banks retrieving credit reports faster after the data layer work.

2019 to 2021 Remote

Logamic

Software engineer

  • Built software infrastructure for managing laboratory hardware in the U.S.
  • WPF, Prism and DevExpress on the desktop, test-driven throughout.
  • Streamlined backend operations in Python and C.

U.S. laboratories running hardware through software built in Slovakia.

2015 to 2021 Remote, hybrid, on site

TSS Group

.NET developer

  • Built a security platform for hotels and buildings on ASP.NET Core, Go and Python.
  • Integrated SOAP and WSDL services, SATEL security protocols and AI-based licence plate recognition.
  • From 2019, support only: I stayed on as the architect of the projects I had built, maintaining them until TSS found a full-time replacement.

7 engineers led on a high-traffic web application.

2019 to 2021

Slovak University of Technology, Bratislava

Information Technology. Left for full-time professional work.

Certification

Oracle Certified Professional

Oracle Database Security Expert

Evolved NDA client Ditec Mastercard CRIF Logamic TSS Group

Half squares: alongside the main role.

evolved.sk, built and run alone

Store, payments, shipping, invoicing and ads, taking real orders.

The evolved.sk home page: the Aftershock pre-workout at 44.99 euros beside Chilliček magnesium at 26.99 euros
The Chens Consulting home page, a Slovak and Chinese trade advisory
Chens ConsultingClient site, SK, EN and Chinesechensconsulting.com
The automated reception product page, with a visitor kiosk beside office turnstiles
e-ReceptionSecurity platform, ASP.NET Core and GoProduct page
codex-mcp-serverFork I maintain, published on npmGitHub

Runs Codex CLI inside Claude Code, Cursor or any MCP client. I added the Claude Code plugin and fixed the sandbox errors and oversized replies that crashed Claude Code. Installs as a Claude Code plugin from its own marketplace.

How a fix ships

The accessibility pass on this site, 7 August 2026. Agents do the typing, I decide what ships.

# audit: contrast, tap targets, scroll cost

2.60:1 orange text on stone, body size needs 4.5

2.84:1 white label on the orange button

2.41:1 tertiary grey on light sections

4.43:1 error text on the alternate surface

1 forced layout per scroll event in the header

3 permanent will-change hints

6 findings, 4 fail WCAG AA

git diff --stat

+ --accent-text: #c2410c;

+ --text-on-accent: #1c1917;

+ --text-muted: #6b6560;

+ --error-text: #c81e1e;

- header reads layout on every scroll event

+ hero bounds cached, refreshed on resize

- will-change: transform; ×3

7 files changed, 345 insertions, 137 deletions

node cdp.mjs --contrast --form --layers

4.75:1 orange text, worst surface

6.17:1 dark label on the orange button

5.27:1 muted grey

5.26:1 error text

3 errors on empty submit, focus moves to the first

0 compositor layers at rest

all checks pass in light and dark

git commit -m "fix: close the accessibility and performance findings from the audit"

[main 6086cbd] 7 files changed

git push origin main

Cloudflare Pages: build queued

~25 s deployed to sskask.pages.dev

curl -s https://sska.sk/ | grep -o '<title>'

live

What I’ve used,
and where

A filled square means I used it in production at that employer.

TSS2015 Logamic2019 CRIF2021 Mastercard2022 Ditec2023 Evolved2024 NDA2025
C# and .NETYesYesYesYesYes
ASP.NET Core, MVC, RazorYesYesYes
Unit tests and TDDYesYesYesYes
WPF, Prism, DevExpressYesYes
SQL Server, EF, DapperYesYes
PythonYesYes
C and C++20YesYes
Angular, React, TypeScriptYesYes
PaymentsYesYes
GoYes
SOAP and WSDLYes
Azure, Azure DevOpsYes
RabbitMQYes
Node, Express, Next.jsYes
PostgreSQL, MongoDB, RedisYes
Claude Code, MCP serversYes
Docker, multi-region infraYes

Slovak, native. English, C1. Russian, spoken comprehension only.

Write to me

Or skip the form: me@sska.sk, github.com/etheaven.

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